The MIMO technology is an effective means for improving spectral efficiency of a communication system by using a multi-antenna technology, and has a very high application value in wireless communications and microwave communications. In a MIMO system, different antenna pairs form multiple different sub-channels, and according to a different transmission feature of a signal on a different sub-channel, a receiving end may decode and identify data on a different transmitting antenna by using a corresponding algorithm, so that an effect that multiple channels of information are transmitted simultaneously on the same frequency band is achieved and spectral efficiency is doubled.
In a distributed MIMO system, antennas are far away from each other, each antenna is connected to an independent outdoor unit(ODU), and each ODU includes a local oscillator(LO). Due to a difference of an LO device in each ODU, multiple channels of baseband signals received by one antenna at a receiving end have different carrier frequency offsets (CFOs, also referred to as frequency offsets), so that it is difficult for a decoding system at the receiving end to converge to a stable decoding state and decoding performance is significantly deteriorated.
In the prior art, a known sequence with a special structure is inserted in transmission data of a baseband signal, for example, a constant amplitude zero auto correlation (CAZAC) sequence, and the sequence is sent on different antennas simultaneously. By using orthogonality between time and space of the sequence, a CFO parameter of the distributed MIMO system may be obtained through calculation, and correction of a signal is implemented according to the CFO parameter, so as to improve the decoding performance.
Because the known sequence is inserted in the transmission data of the baseband signal, effective transmission of the data is affected; and furthermore, a process of calculating the CFO parameter of the distributed MIMO system according to the known sequence is intermittent and does not have a dynamic tracing feature.